At present, the printing of still images sensed using a digital camera or the like is common. Moreover, it is also possible to print moving images sensed with a digital camera and the like, in which case one desired frame from among the recorded images is extracted and a print made based on such single frame still image.
However, moving images sensed with a digital camera or the like usually have a resolution of 640 pixels horizontally×480 lines vertically (VGA—Video Graphics Array), which is not a high enough resolution for printing as a good quality still image. In addition, since the moving images are assumed to be viewed on a display, the color bandwidth of the video signal is limited when recorded. As a result, the color bandwidth of the single-frame still image extracted from the moving image-recorded video signals also is reduced by band limitation, so that the quality of the picture is poor not only in terms of the resolution (the number of pixels) but also in terms of the amount of color information. Therefore, moving images are generally unsuitable for purposes of printing. In order to print moving images of high picture quality, it is necessary to record at high resolution with a wideband color signal.
Japanese Patent Application Laid-Open No. 07-322295 proposes transmitting an RGB still image signal in addition to a band-limited YUV moving image signal along a transmission path for transmitting band-limited moving images, enabling an image output device such as a video printer to obtain a high quality still image by separating out the still image signal.
In addition Japanese Patent Application Laid-Open No. 2001-359117 proposes inputting an image signal containing color signals and a luminance signal from an image input unit and, if the image signal is a moving image, first, reducing the data amount of the color-difference signal of the image signal and compressing it together with the luminance signal, and then shifting up and encoding a designated area in the image so as to improve the picture quality of the designated area.
However, because the video signal transmission apparatus described in Japanese Patent Application Laid-Open No. 07-322295 transmits a still image signal composed of component video signals in addition to the band-limited moving image signal, transmission volume increases and thus requires a wideband memory bus. Therefore, if the bandwidth of the memory bus is narrow, at video signal transmission the band of memory bus may be overloaded, leading in the worst case to a loss of transmission. When that happens, the image compression ratio increases and the amount of data of the video signal to be transmitted is reduced, leading to the same deterioration in picture quality that is a problem with the conventional art.
In addition, with the image processing apparatus described in Japanese Patent Application Laid-Open No. 2001-359117, an image of high picture quality is generated by shifting up and encoding a designated area of the image. As a result, however, the remainder of the image is not of high quality and thus the same problem that exists in the conventional art remains, meaning that the picture quality is not good enough for output to a color printer as a still image.
Moreover, since a high quality image is output to a display device at the same time as a high quality moving image is recorded, the band of the memory bus is overloaded at video signal transmission. As a result, the same problem arises as with the video signal transmission apparatus of Japanese Patent Application Laid-Open No. 07-322295